Radiative Shock-induced Collapse of Intergalactic Clouds

By P. Chris Fragile, S. Murray, Peter Anninos, W. V. van Breugel. 2003

132 citations recorded by the source corpus.

Accumulating observational evidence for a number of radio galaxies suggests an association between their jets and regions of active star formation. The standard picture is that shocks generated by the jet propagate through an inhomogeneous medium and trigger the collapse of overdense clouds, which then become active star-forming regions. In this contribution, we report on recent hydrodynamic simulations of radiative shock-cloud interactions using two different cooling models: an equilibrium cooling-curve model assuming solar metallicities and a nonequilibrium chemistry model appropriate for primordial gas clouds. We consider a range of initial cloud densities and shock speeds in order to quantify the role of cooling in the evolution. Our results indicate that for moderate cloud densities (≳1 cm-3) and shock Mach numbers (≲20), cooling processes can be highly efficient and result in more than 50% of the initial cloud mass cooling to below 100 K. We also use our results to estimate the final H2 mass fraction for the simulations that use the nonequilibrium chemistry package. This is an important measurement, since H2 is the dominant coolant for a primordial gas cloud. We find peak H2 mass fractions of ≳10-2 and total H2 mass fractions of ≳10-5 for the cloud gas, consistent with cosmological simulations of first star formation. Finally, we compare our results with the observations of jet-induced star formation in "Minkowski's Object," a small irregular starburst system associated with a radio jet in the nearby cluster of galaxies Abell 194. We conclude that its morphology, star formation rate (~0.3 M☉ yr-1) and stellar mass (~1.2 × 107 M☉) can be explained by the interaction of a ~9 × 104 km s-1 jet with an ensemble of moderately dense (~10 cm-3), warm (104 K) intergalactic clouds in the vicinity of its associated radio galaxy at the center of the galaxy cluster.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/89d7bfa1328eff7a1e1abe60b70ae44a9e83de31

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Citations in the corpus

The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations (2015, background): “…problem in the study of the ISM, not least because of the extreme resolution and dynamic range demands of the problem: the losses are typically established on scales significantly smaller than a parsec (e.g. Mellema, Kurk & Röttgering 2002; Fragile et al. 2004; Yirak, Frank & Cunningham 2010).”
Fast neutral outflows in powerful radio galaxies : a major source of feedback in massive galaxies (2005, background): “Such rapid cooling is indeed predicted by recent numerical simulations of jets impacting on gas clouds (Mellema et al. 2002, Fragile et al. 2004).”
Outflows in Active Galactic Nucleus/Starburst-Composite Ultraluminous Infrared Galaxies (2005, background): “On more local scales, jets from AGNs at both low and high redshift have been shown to induce star formation by shocking dense clouds of gas (e.g., Bicknell et al. 2000; Mould et al. 2000; Rejkuba et al. 2002; Fragile et al. 2004).”
Evidence for powerful AGN winds at high redshift: dynamics of galactic outflows in radio galaxies during the “Quasar Era” (2008, background): “…problem (e.g., Binney & Tabor 1995; Ruszkowski & Begelman 2002; Kaiser & Binney 2003), but are also addressing the impact of the jets in individual radio galaxies (e.g., Mellema et al. 2002; Fragile et al. 2004; Saxton et al. 2005; Krause 2005; Sutherland & Bicknell 2007; Krause & Alexander 2007).”
On the Hydrodynamic Interaction of Shock Waves with Interstellar Clouds. II. The Effect of Smooth Cloud Boundaries on Cloud Destruction and Cloud Turbulence (2005, background): “477 fields (Mac Low et al. 1994; Jones et al. 1996; Fragile et al. 2005), radiative cooling (de Gouveia Dal Pino 1999; Horváth & Ziegler 1999; Mellema et al. 2002; Fragile et al. 2004; Melioli et al. 2005), and thermal conduction (Orlando et al. 2005).”
Quasar feedback: more bang for your buck (2009, background): “…velocities of the cloud, then the cloud will be stretched and ‘shredded’ by a combination of Rayleigh–Taylor and Kelvin–Helmholtz instabilities on a time-scale approximately a few tcc (see e.g. Klein et al. 1994; Xu & Stone 1995; Fragile et al. 2004; Orlando et al. 2005; Nakamura et al. 2006).”
Experimental astrophysics with high power lasers and Z pinches (2004, background): “A particularly interesting case, pointed out recently by Fragile and co-workers, is the jet-induced star formation in “Minkowski’s object,” a small irregular starburst system associated with a radio jet in the nearby cluster of galaxies Abell 194 Fragile et al., 2004 .”
Relativistic jet feedback – III. Feedback on gas discs (2018, background): “Typically, a cloud is expected to survive a few cloud crushing times (Fragile et al. 2004; Scannapieco & Brüggen 2015), where the cloud crushing time is the time for the incumbent shock to pass the length of the cloud.”
Jet-induced star formation in gas-rich galaxies (2011, background): “Once they get shocked by the blast wave, they are compressed but lose their pressure support almost instantly, which prevents later re-expansion (see also the simulations by Mellema et al. 2002; Fragile et al. 2004).”